1. Field
Aspects of the present disclosure relate to cathode active materials, cathodes including the cathode active materials, and lithium batteries including the cathodes.
2. Description of the Related Art
In line with the development of smaller and higher-performing devices, high-energy-density, in addition to miniaturization and light weight, has been regarded as an important factor for lithium batteries. In addition, in order to be applied to electric vehicles, the cycle characteristics at room temperature and high temperature have also been regarded as important factors for lithium batteries. To manufacture such lithium batteries, research for various cathode active materials has been undertaken.
Lithium cobalt oxides are commonly used as cathode active materials. However, lithium cobalt oxides are expensive, the effective capacity of lithium cobalt oxides is 50% of the theoretical capacity, and the driving voltage of lithium cobalt oxides is about 4 V. Examples of lithium cobalt oxides include LiCoO2.
Lithium manganese oxides have an effective capacity similar to that of lithium cobalt oxides and a driving voltage of about 4 V, and are inexpensive and stable. However, lithium manganese oxides have poor cycle characteristics. Examples of lithium manganese oxides include LiMn2O4.
Spinel compounds formed by substituting some manganese contained in lithium manganese oxides with other metals generate a high voltage of about 5 V. Such spinel compounds have poor cycle characteristics at high temperature. Examples of such spinel compounds include LiNi0.5Mn1.5O4.
Thus, there is a need to develop a cathode active material that produces a high voltage and has excellent cycle characteristics at room temperature and high temperature.